The present invention relates to a method for optimizing the landing of an aircraft on a runway, and a corresponding optimization device.
The present invention applies to a method for computing an optimal final slope for the landing of an aircraft, of “A-IGS” (Adaptive Increased Glide Slope) type.
From the documents US-2012/0232725 and FR-2 972 541, the disclosures of which are incorporated herein by reference, a method and a device are known for optimizing the landing of an aircraft on a runway, said landing comprising an approach phase, defined by an approach axis to be followed with which is associated a predefined ground slope and a flare phase. This usual method is such that:                in a preliminary step:        
from performance levels and characteristics specific to said aircraft, a target vertical speed is defined relative to the ground which is to be applied to said aircraft on initiation of the flare phase; and
an optimized ground speed is determined, as a function of said target vertical speed and of at least one outside parameter, associated with the approach axis, which is greater than or equal to the predefined ground slope, and                upon interception, by the aircraft, of the approach axis, said aircraft is guided so that it follows the determined optimized ground slope, associated with said approach axis, and that it reaches the target vertical speed previously defined on initiation of the flare phase.        
Thus, by this known method, the ground slope of the approach axis is optimized (relative to the ground slope published in the standard operating procedure) from a target vertical speed predefined using characteristics specific to the aircraft. By setting the ground vertical speed of the aircraft on initiation of the flare (at approximately 50 feet) to a previously defined nominal target value, this usual method makes it possible to secure the final approach phase by proposing a more constant, repetitive and easy flare, while increasing the slope by exploiting the conditions of the approach concerned with improving the environmental aspects, without imposing operational constraints.
Energy management on approach depends greatly on factors specific or external to the aircraft influencing the deceleration capabilities of the aircraft. In particular, the weight of the aircraft and the weather conditions are factors which influence the deceleration capability. Particular attention on the part of the crews is required with respect to the monitoring of the flight parameters and, if necessary, the application of corrective actions such as early extension of the high lift flaps of the gear and/or use of the air brakes.
However, the deceleration management can be made more difficult when the slopes are increased, for example for obstacle avoidance considerations.
Similarly, the increased slope proposed by the computation of the optimized slope, of A-IGS type, which is based solely on the final approach speed and the target vertical speed, can, in certain cases, result in approaches being flown that are too steep, which would increase the risk of non-stabilized approach.